It uses a couple of useful timings to throw Terran of balance, allow the zerg to expand safely, and transition into endgame compositions.
There are replays, walk throughs, and build orders in the guide. A Brief summary is a speeding attack at 6:00 before hellions are available, a baneling/speeding/roach push at 12:30 then droning the third base, followed by 3/3 Crack-lings, banelings and ultralisks.

I find that some variation with infestors are a lot stronger vs BIO if you delay the third aggression phase. I Also feel that at any point you can transition out of this build and tech differently if you see the Terran opponent doing something other than standard 3cc play. I would appreciate some input!!!

No one cared who I was until I took the helm.
Commander of the CFS-Excalibur
:|: Strength~Pride~Unity :|:

I have read threw this before and it is very helpful. I would consider this a must read for all zerg players struggling with ZvT. I have beating 90% of terran players I've faced with it. Glad to see someone post this on here because it is very good quality and the explanations are spot on.

It is my general strategy for ZvT. Unless mech is scouted this is my strat 100% of the time.
Here is a couple replays of me executing this build. My timings are off and I forget 1 or 2 upgrades and a gas here or there, but the strategy is very easy to execute as a whole. I often add in a spire to this build for muta switches or brood lords if the terran turtles on 2base and refuses to leave.